As used in this context, a hearing aid is understood as generally comprising a device with an input transducer for transforming an acoustic input signal into a first electrical signal, a signal processor for generating a second electrical signal based on the first electrical signal, an output transducer for conversion of the second signal into sound, and a battery for supplying power to the signal processor.
Behind-the-ear (BTE) hearing aids is the term commonly used for a hearing aid having most of the components arranged inside a curved housing adapted for resting over the external ear (the pinna), usually combined with a plug for insertion in the ear canal and with an acoustic conduit for conveying the amplified sound from the receiver placed in the BTE housing and to the plug.
Within the present context, an adapter shoe for a hearing aid designates a device for optional fastening to a hearing aid. The adapter shoe usually serves the purpose of temporarily attaching equipment for use together with the hearing aid, for implementing some specific functionality not incorporated inside the hearing aid, or for providing a connection between the hearing aid and external equipment. The adapter shoe may incorporate means for providing electrical connections to appropriate contact pads of the hearing aid.
An accessory of relevance to the invention comprises a radio receiver such as an FM receiver adapted for receiving an FM radio signal, converting the FM signal into an audio signal and providing the audio signal to the hearing aid, where the audio signal is fed into the hearing aid input circuitry. Other accessories of relevance comprise wireless receivers in general, infrared receivers, connectors for interfacing with other connector systems, audio cables for connection to an external source or another hearing aid, and a programming cable for programming the hearing aid.
U.S. Pat. No. 4,947,439 provides a hearing aid with a contact arrangement for electrically connecting a battery power supply to electrical components of the hearing aid. The battery power supply is carried in a compartment which is pivotally attached to the hearing aid housing and pivoting of the compartment places the battery into contact with spring contacts to thereby provide electrical power to the electrical components of the hearing aid and to thereby turn on the hearing aid.
DE-U-29916350 shows a hearing aid with a pivotable battery compartment adapted for serving as a power switch and with a sliding element serving as a lock for the switch. The battery compartment is provided with a protruding lip to facilitate manipulation.
U.S. Pat. No. 5,588,064 shows a hearing aid with a battery compartment formed as a drawer or a holder. The holder has a pivot point about which the holder rotates when it is pushed into the housing. The pivoting motion, or at least a part of it, may be used to slide the battery terminals over a set of contacts, thereby allowing the motion also to be used for performing switching functions
WO-A1-02/51203 shows a communication system comprising a housing adapted for placement behind an ear, the housing comprising a battery compartment which is pivotally mounted on the housing, and which has a recess. The communication system comprises a communication element, which has a protruding element adapted for engagement with the recess in the battery compartment in such a manner that the communication element may be pivoted together with the battery compartment.
WO-A-2004/073351 shows a hearing aid with a removable battery compartment, wherein the battery compartment can be pivoted to manipulate a power switch and to allow exchange of the battery, and where there is a security lock to prevent accidental loss of the battery.
WO-A-2004/080123 shows a combination unit for attachment to a hearing aid, comprising an adapter shoe and an accessory. The hearing aid is provided with a pivotable battery compartment for use as a power switch. The adapter comprises a shoe, i.e. a sleeve-like structure, adapted to partially enclose the lower portion of the hearing aid. The adapter shoe is provided with small ribs for engaging grooves in the hearing aid housing for mechanical engagement. The sleeve leaves open access to part of the rear side of the hearing aid housing in order to allow manipulating the hearing aid power switch.
Access to manipulating the switch is favored by many users. There may, however, be users preferring some way of blocking that access. This may e.g. be the case in a classroom situation with minors, or others, not knowing how to operate the switch, where it would be preferred to have a teacher assume responsibility of switching on the hearing aid with accessories.
The adapters will by inherently be provided as an optional accessory, suitably tailored to the specific shape of hearing aid housing. As the greater part of users will use the hearing aids without adapters, there is an emphasis on providing an attractive design of the hearing aid housing on its own, making it less attractive to provide the housings with very conspicuous connection details. This can make it difficult to devise sturdy connections that will avoid accidental loss of the adapters. Therefore, there is great interest to devise adapters that can cling on to very tiny connection details, e.g. shallow grooves and small ribs as may be there.